1. Field of the Invention
The present invention relates to magnetic sensing elements used for hard disk drives, magnetic sensors, etc. More particularly, the invention relates to a magnetic sensing element in which side reading can be prevented, read sensitivity can be improved, and gap narrowing is enabled, and which can be easily and properly fabricated, and to a method for fabricating such a magnetic sensing element.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 9-128714 (patent document 1) discloses a magnetic transducer in which a plurality of ferromagnetic layers and spacer layers are laminated in the thickness direction, each spacer layer being interposed between the two adjacent ferromagnetic layers, and as means for controlling the magnetizations of the individual ferromagnetic layers, exchange coupling layers are placed adjacent to the top and bottom ferromagnetic layers.
According to patent document 1, the exchange coupling layers are composed of FeMn, NiMn, or the like. By producing exchange coupling magnetic fields between the top ferromagnetic layer and its adjacent exchange coupling layers and between the bottom ferromagnetic layer and its adjacent exchange coupling layers, the magnetization directions of the individual ferromagnetic layers are controlled.
The exchange coupling layers are formed on a substrate with a predetermined space therebetween, and the ferromagnetic layer is deposited over the substrate and the exchange coupling layers which protrude from the substrate. The spacer layers and the ferromagnetic layers are alternately deposited further thereon.
That is, according to patent document 1, the ferromagnetic layers and the spacer layers are deposited on an uneven surface.
However, if the ferromagnetic layers and the spacer layers are deposited on an uneven surface, it is not possible to form the ferromagnetic layers and the spacer layers with predetermined thicknesses, and also the following problems occur.
That is, the magnetization of the central region of the ferromagnetic layer disposed between the exchange coupling layers is also easily pinned at the sides by extra magnetic fields from the exchange coupling layers, which may result in a decrease in sensitivity to an external magnetic field.
In the structure of the magnetic transducer in patent document 1, there is also a possibility that the magnetization of the ferromagnetic layer disposed on the exchange coupling layer, which should be strongly pinned, may be easily rotated in response to an external magnetic field.
Although patent document 1 does not disclose a specific fabrication method, a fabrication method can be assumed from the structure of the magnetic transducer of patent document 1 in which the exchange coupling layers are formed with a predetermined space therebetween in the track width direction on the substrate, and then the ferromagnetic layers and the spacer layers are deposited. That is, since it is not possible to form the exchange coupling layers and the ferromagnetic layer continuously in the same chamber, the magnitudes of the exchange coupling magnetic fields produced between the ferromagnetic layer and the exchange coupling layers are weak. Consequently, the magnetizations of the side regions of the ferromagnetic layer are easily rotated in response to the external magnetic field, which may result in side reading.
The magnetizations of the individual ferromagnetic layers are thought to be not properly controlled simply by depositing the individual layers. That is, it is unclear from the content of patent document 1 how the use of the magnetic transducer is implemented.